Add `slave_alloc_update` tool.

masters/master.chromiumos/master.cfg

 # -*- python -*-
 # ex: set syntax=python:
 
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # This is the buildmaster config file for the 'chromeos' bot. It must
 # be installed as 'master.cfg' in your buildmaster's base directory
 # (although the filename can be changed with the --basedir option to
@@ skipping 279 matching lines @@
       status_header='%(steps)s failed on "%(builder)s"',
       subject='buildbot trooper alert on %(builder)s (%(projectName)s)',
       extraRecipients=['chrome-troopers@google.com'],
       sheriffs=['sheriff'],
       lookup=master_utils.FilterDomain(),
       use_getname=True))
 
 if not ActiveMaster.is_production_host:
   # Save our slave pool state. This is populated when our 'slaves' variable
   # gets generated.
-  chromiumos_board_config.slave_allocator.SaveState(list_unallocated=True)
+  chromiumos_board_config.slave_allocator.SaveState()
   slave_map = chromiumos_board_config.slave_allocator.GetSlaveMap()
   if slave_map.unallocated:
     log.msg("The following slaves were not allocated: %s" % (
         sorted(slave_map.unallocated),))
 
   # Dump the current configuration.
   master_utils.DumpSetup(c)
 
   # Disable 'auto_reboot' on slaves for local testing.
   for builder in c['builders']:
     builder['auto_reboot'] = False